Radon daughter dosemeter

Abstract

The invention provides a radon daughter dosemeter made up of a cyclone, a filter in a filter holder and a radiation detector spaced from the filter. The filter is arranged to filter dust and aerosol particles from air issuing from the air outlet of the cyclone, and the detector is arranged to detect radiation from dust and aerosol particles on the filter. The invention also provides a method of monitoring radiation exposure of persons; and an electrochemical etching cell for the etching of detectors used in the dosemeter.

We claim: 
     
       1. A radon daughter dosemeter which comprises: a cyclone having an air inlet, a solids outlet and an air outlet, for separating non-respirable dust and aerosol particles from air;   a filter mounted on the cyclone for filtering respirable dust and aerosol particles from air passing through the cyclone from the air inlet to the air outlet; and   a detector mounted on the cyclone for detecting radiation emitted by radon daughters attached to dust and aerosol particles on the filter.   
     
     
       2. A dosemeter as claimed in claim 1, which is of portable construction, and comprises a portable electrochemical cell-driven air suction pump connected to the air outlet of the cyclone, for suction of air through the cyclone. 
     
     
       3. A dosemeter as claimed in claim 1, in which the detector is a solid state nuclear track-etch detector for detecting α-particle radiation. 
     
     
       4. A dosemeter as claimed in claim 3, in which the detector comprises a plastics material capable of being penetrated by α-particles having sufficient kinetic energy, to leave tracks, which detector can be etched to render the tracks detectable and countable. 
     
     
       5. A dosemeter as claimed in claim 3, in which the filter and detector are flat and planar in shape, spaced from each other in parallel opposed relationship. 
     
     
       6. A dosemeter as claimed in claim 3, in which the air outlet of the cyclone has a hollow circular-cylindrical filter holder releasably attached thereto, the filter being a circular disc and being located as a partition in the filter holder between an inlet to the filter holder which communicates with the cyclone air outlet, and an air outlet from the filter holder. 
     
     
       7. A dosemeter as claimed in claim 6, in which the detector is circular in outline, being located as a partition in the holder, upstream with regard to air flow, from the filter, the detector having an air flow opening therethrough. 
     
     
       8. A dosemeter as claimed in claim 7, in which a radiation-absorbing discriminator is located between the filter and detector, for reducing the number of tracks detected by the detector. 
     
     
       9. A method of monitoring the degree of exposure to which a person is subjected by radiation from radon daughters, which method comprises the steps of passing air in the person's environment through a cyclone to separate nonrespirable dust and aerosol particles from the air, passing the air issuing from said cyclone through a filter to filter respirable dust and aerosols from the air passing through the cyclone, and detecting radiation emitted by radon daughters attached to dust and aerosol particles filtered from the air by the filter. 
     
     
       10. A method as claimed in claim 9, which comprises mounting the cyclone, filter and detector on the person, so that said radiation is monitored in the immediately vicinity of the person, the method including the step of using a track-etch detector for detecting the radiation, and including the subsequent steps of etching the detector and counting tracks formed thereon.